Zhang C T, Zhang R
Department of Physics, Tianjin University, Tianjin 300072, China.
Biopolymers. 2000 Jun;53(7):539-49. doi: 10.1002/(SICI)1097-0282(200006)53:7<539::AID-BIP2>3.0.CO;2-2.
A secondary structure sequence is a symbolic string composed of three kinds of letters, indicating the helix, strand, and coil (including turns), respectively. A graphic representation for this abstract symbolic sequence is proposed here, called the S curve. The S curve is the unique representation for a given secondary structure sequence in the sense that the sequence and the S curve can be uniquely determined from the other. Therefore, the S curve contains all the information that the secondary structure sequence contains. Different geometrical properties of the S curve are studied in details, which reflect the basic characteristics of the secondary structure sequences. The S curves are used to display, analyze, and compare the secondary structure sequences. Detailed application examples are presented. One advantage of the S curve methodology is that the main patterns of a given secondary structure sequence can be grasped quickly in a perceivable form. This is particularly useful in the cases in which longer sequences are involved and structures of proteins are unknown.
二级结构序列是由三种字母组成的符号串，分别表示螺旋、链和卷曲（包括转角）。本文提出了一种针对这种抽象符号序列的图形表示法，称为S曲线。S曲线是给定二级结构序列的唯一表示，因为序列和S曲线可以相互唯一确定。因此，S曲线包含了二级结构序列所包含的所有信息。详细研究了S曲线的不同几何特性，这些特性反映了二级结构序列的基本特征。S曲线用于显示、分析和比较二级结构序列。给出了详细的应用示例。S曲线方法的一个优点是，可以以一种可感知的形式快速掌握给定二级结构序列的主要模式。这在涉及较长序列且蛋白质结构未知的情况下特别有用。
